Information playback systems frequently utilize a stylus for reading signals from the surface of an information record, typically a plastic disc, that contains stored video and audio information. In some systems the information record has a fine spiral groove to guide the tip of a stylus that contains a thin electrode. In these systems, the stylus tip is made of a material having sufficient hardness to withstand the abrasion caused from tracking the groove. Materials which possess such hardness, for example diamond, generally have a crystallographic structure which presents surfaces exhibiting different qualities depending upon which crystallographic planes the surfaces are oriented along. Consequently, in manufacturing styli from these crystallographic materials for use in video disc playback systems, it is important to know and maintain the tip orientation during the various processing steps in order to achieve uniform styli of high quality.
The orientation of the stylus tip is usually controlled during processing by handling the longer and relatively larger shank of the stylus, at the end of which the tip is disposed. The stylus may be fabricated entirely from the crystallographic material, so that both the tip and the shank comprise one integral piece of material. In this case a planar surface of the shank, parallel to the shank axis, is formed along a predetermined crystallographic plane. Since the tip is fabricated from the same integral piece of material, the orientation of the tip may be controlled by utilizing the longitudinal surface of the shank for alignment. However, making a long-shanked stylus entirely from the same material may become expensive, particularly when the tip material, for example diamond, exceeds the cost of other suitable materials from which the shank can be made.
In order to reduce manufacturing costs, the shank of the stylus may be made from a different material which is less expensive than the crystallographic tip material. For example, a small diamond stone may be mounted at the end of a relatively long metallic shank, such as a cylindrical titanium rod. However, in the mounting process it is difficult to orient the diamond stone along a desired crystallographic plane with respect to the metallic shank, and to maintain this same orientation for a plurality of styli. The present invention provides a novel technique for manufacturing a plurality of styli having shanks made from a material different from the crystallographic tip material, whereby the orientation of the crystallographic plane in each tip with respect to the supporting shank is uniform for all styli.